The claim: The crust of bread is more nutritious than the bread itself.
The facts: The belief that the crust is healthier for you than the soft inside of bread appears to be based on a well-publicized study from 2002 in the Journal of Agricultural and Food Chemistry. It found that bread crust contained higher amounts of an antioxidant, called pronyl-lysine, than breadcrumbs (made from the inside part of the bread) or the flour used to make the bread. The researchers, at the Institute of Human Nutrition and Food Science in Kiel, Germany, tested the effect of pronyl-lysine on human intestinal cells in the lab and found that it increased the activity of enzymes linked to cancer prevention.
The formation of pronyl-lysine during baking is the result of a chemical reaction you may remember from high school chemistry—the Maillard reaction. It’s triggered by heat and it’s what gives foods their brown color, crusty texture, and distinctive flavor. Another type of antioxidant, called melanoidins, are also formed during the Maillard reaction. It stands to reason, then, that the end piece of a loaf of bread, which is often tossed in the garbage along with the wrapper, would contain even higher amounts of pronyl-lysine than a regular crusted slice of bread.
However, the Maillard reaction that creates these potential disease-fighting antioxidants also produces a not-so-desirable compound, called acrylamide. Possible risks associated with acrylamide consumption include toxic effects on the brain, genes, and reproductive tract and an increased risk of cancer. The higher the temperature and the longer the food is baked, the more acrylamide is formed, so toasted bread contains higher amounts than untoasted bread.
To put things into perspective, most foods naturally contain potential cancer promoters, as well as cancer fighters—and analyses from the FDA have found that other foods contain much higher levels of acrylamide than bread. For instance, French fries and potato chips can have up to 20 times the acrylamide level of a slice of toasted whole-wheat bread.
Bottom line: So should you eat the crust for its extra pronyl-lysine, or cut it off your kids’ lunches and serve only crustless finger sandwiches at get-togethers to reduce acrylamide exposure? Unfortunately, there’s no way to know if the potential benefits of antioxidants in the crust outweigh the possible adverse effects of acrylamide (or vice versa), or if it’s a zero-sum game. But if you choose whole-grain bread—with its fiber, B vitamins, magnesium, iron, selenium, and other healthful compounds—over refined white bread, the benefits likely outweigh the risks, crust or no crust. And one thing is certain: Cutting off the crust wastes food.